IMO It would be too stressful for a baby because they'll have to watch out for predators, cars, and birds and other dangers, plus the beardie might dart at any moment if it's a baby (and trust me, they're super fast). IMO I would just wait until it's a bit older and more settled in.

Slave to Four Beardies, one Crested gecko, a Ball Python, one Betta fish, and a Cat.(R.I.P Thor & Cisco, You two will always be in our hearts).[Click image to enlarge]

My babies went outside from within a week or two of when they hatched. As long as you keep an eye on them it's fine and they get used to the outdoors pretty quickly. Little guys do well in a child's pool but you have to be sure it's not too hot out and that you provide artificial shade. Here's a picture of a group of babies. Larger dragons need a screened cage , they are able to easily jump out of the plastic pool.